Combined Free- and Forced-Convective Heat Transfer and Fluid Flow in Rotating Curved Rectangular Tubes

A theoretical study is presented for combined free- and forced-convective heat transfer and fluid flow in curved rectangular tubes rotating about an axis through the center of curvature of the tube. The analysis is performed under the conditions that the flow is thermally and hydrodynamically fully developed, and the axial wall heat flux is uniform with a peripherally uniform wall temperature. The governing equations are solved numerically, and effects of the aspect ratio, radius ratio, Prandtl number, a nondimensional parameter representing the effects of Coriolis forces, Grashof number, and Dean number on the flow and heat-transfer characteristics are presented for velocity and temperature distributions, streamlines and isotherms, local and mean friction factors f and Nusselt numbers Nu. The effects of the first two geometrical parameters are minor. However, an increase in the last three force parameters enhances both f and Nu greatly. An effect characteristic of the Coriolis forces is that they cause a great increase in f, while the enhancement of Nu is much less remarkable.